Model aeroplane motor starter



Feb. 1, 1955 E. MCELROY 2,

MODEL AEROPLANE MOTOR STARTER Filed March 6. 1950 fig-.1.

lnvented United States Patent MODEL AEROPLANE MOTOR STARTER Isaac Erwin McElroy, Van Nuys, Calif.

Application March 6, 1950, Serial No. 147,983

9 Claims. (Cl. 123-185) My invention relates to a starter for internal combustion model airplane motors in which rotating means temporarily engage the crankshaft, propeller, propeller nut, or a special nose piece adapted for the purpose, to turn the engine. through several revolutions; and to instantly disengage and release the entire starting mechanism from the motor and plane when the engine starts. Nose pieces to lessen head resistance have long been in use and are known in the model industry as spinners. My only change in this customary practice is to provide the spinner with engagement means in order to turn the crankshaft. And the objects of my invention are,

1st, to provide a safe means for rotating the crankshaft through several complete revolutions, instead of flipping the prop through a single compression with the finger as has been the practice by fans for the past fifteen years, and risk having said finger practically removed or severally injured when the motor fires too weakly to carry over, then backfires from the next compression, or fires forward too rapidly to get the finger out of the way.

2nd, to get all mechanical parts of the rotating means entirely away from the motor and plane instantly when the motor starts and have them still under the control of, and supported by, the operator, without the hands, or person, being near the whirling propeller.

3d, little or no lateral or undue stress on the delicate mechanism of the plane itself.

4th, to turn the motor far enough and fast enough to avoid flooding, or to dry out a flooded condition if it has already developed.

5th, to bring a practical starting means within the economic reach of the average model airplane fan.

6th, to spin the motor rapidly, so that it can be started more nearly at the normal fuel adjustment, thus lessening the tendency to flood, which is the main difficulty encountered with all model engines.

7th, a starter light enough and small enough to be carried in any modelers pocket.

8th, a practical starter for the model engine enthusiast requiring no springs, gears, or expensive batteries and other accessories.

9th, easy adaptability to practically any type or make of model motor.

10th, inexpensive durable service.

11th, utmost simplicity. Any child of ten can operate it.

Still more specific and detailed objects of the invention will be disclosed in the course of the following specifications.

I attain these objects by the mechanism illustrated in the accompanying drawing in which,

Figure l is a side view of a preferred type of spinner;

Fig. 1a is an end view of the spinner shown in Fig. 1;

Fig. 2 is a side view of the assembled starter in engagement with the spinner shown in Fig. 1, a portion of the apparatus being broken away and shown in section;

Fig. 2a is a front view of the apparatus shown in Fig. 2; and

Fig. 3 is a perspective view showing the starter and spinner before engagement.

Referring now to the drawings: The spinner, Fig. l, threaded as shown at 1, threads upon the end of the crankshaft 2, and is tightened against the propeller by inserting a rod or nail in the hole 3 thereby binding the crankshaft 2, the propeller 4 and the spinner with them into one integral unit. The shape of this spinner is not important except to offer as little wind resistance as possible and to allow the rotating means easy disengagement.

2,700,968 Patented Feb. 1, 1955 This spinner is fitted with engagement pins or projections 5, preferably as few in number as will hold the starting pulley Fig. 2 squarely in position. Although one would serve, the static balance would be aflected, therefore all drawings show two engagement pins.

A hollow pulley or rotating means, Fig. 2, is adapted to fit closely over the spinner at the front and back for rigidity and alignment and to engage the pin or pins 5 of the spinner, Fig. l, by means of recesses as shown at 6 in Fig. 2 and Fig. 3. These recesses 6 are helically arranged, and engage the pins 5 to hold the pulley securely while starting the motor. The helically arranged recesses 6 establish an overrunning connection between the pulley member and the spinner 1 so that when the motor starts, the pins 5 move out of the recesses 6 and urge the pulley structure longitudinally away from the spinner 1.

The perimeter of the pulley, Fig. 2 is flanged front and rear in order to define a channel to receive and retain a strong cord, thong, or other flexible medium to act as a rotating means when wound upon it. To attach said rotating means, holes or slots 7 are provided, preferably through the face of the pulley. The cords are inserted and knotted on the inside of the rim, one on each side. A single cord may be used if passed through both holes allowing about three feet on either side. The cords are then to be wound upon the pulley doubly and parallel in the direction of rotation. One cord is then grasped in either hand and force exerted to spread the hands apart, which rotates the pulley and with it the spinner and crankshaft through several revolutions, and when the motor starts, the pulley disengages and frees itself from the spinner and is supported on the taut cords between the hands entirely free from the whirling prop. I have found it desirable to divide the channel for the rotating means into two parts by means of a center flange as shown at 8 in Fig. 2. One cord is wound in one channel and the other in the remaining channel. Both may be wound at the same time if desired, the center flange serving as an assistance in winding, to avoid overlapping one cord upon the other and to prevent tangling while unwinding.

I am aware that prior to my invention, small internal combustion engines, such as outboard motors and the like have been started with a strap or strong cord wrapped about the flywheel as a rotation means; or upon a drum or spool secured to the crankshaft. I therefore do not claim to have originated the principle. Nor can I broadly claim disengaging starting means. Automobiles have been so equipped for many years.

It is to be noted however, that in my invention the pulley and rotating means are at no time any part of the running motor; and that by using two cords and winding the cords doubly, that a double leverage is obtained, one cord acting upon each side of the pulley in opposite directions. This permits the use of a pulley of only half the diameter with twice the number of turns and but little more than one fourth the weight of one that would be required for the same force exerted upon a single cord.

Moreover, since the force exerted by one hand is counterbalanced by equal force from. the other hand, there is no force tending to drag the plane sideways or to put undue strain upon the frail construction used in model planes in order to obtain the necessary torque, as would be the case if a single cord were used. These features are necessary to make the starter feasible and practical, and they produce a new, novel, inexpensive and useful article which has been lacking to the model airplane enthusiast since model airplane motors first appeared on the market nearly twenty years ago.

Without arguing the relative merits of the means employed as shown in the drawings, it will be apparent that much in my disclosure is but a matter of detail and merely illustrative, such as pins for engagement elements, since other means may be employed. This offers much opportunity for change without affecting the principle or scope of my invention. With this in mind, I do not wish to be restricted to the details described, but to be limited only by the scope of appended claims.

What I claim is:

1. In a device of the character described: a pair of rotary members, one of said members being adapted to be carried by a shaft; said members having means forming an overrunning coupling between them, comprrsing one or more projections carried by one of the members, and means forming one or more helical slots provided with one open end and engageable with said one or more projections; and a pair of flexible means for exerting a couple on the other of said members, whereby the forces exerted upon said members by said couple exerting means are in balance.

2. In a device of the character described: a pair of rotary members, one of said members being adapted to be carried by a shaft; said members having means forming an overrunning coupling between them; a pair of flexible means for exerting a couple on the other of said members for rotating said other member in an angular direction corresponding to movement of said other memher into coupling relation with said one member, said flexible means thereby exerting rotation producing forces upon said members that are in balance; and means forming separate annular spaces on said other of said members for accommodating said flexible means respectively.

3. In a device of the character described: a first rotary member adapted to be secured to a shaft; 21 second rotary member for driving said first rotary member; said members having means forming an overrunning connection between them, comprising a plurality of equi-angularly spaced projections carried by one of the members and means forming a corresponding plurality of helically arranged recesses carried by the other member, each of said recesses being open at one end and engageable with said projections respectively; and means for exerting a couple 1 on the other of said members for rotating said members, whereby the forces exerted upon said members by said couple exerting means are in balance.

4. In a device of the character described: a pair of rotary members, one of said members being adapted to be carried by a shaft; said members having means forming an overrunning coupling between them; the other of said members having means forming a pair of circumferential channels axially spaced from each other; and flexible means secured to said other member and having free ends adapted to be wound in the channels respectively for applying a couple to said other member, whereby the forces exerted upon said members by said flexible means are in balance.

5. In a device of the character described: a pair of rotary members, one of said members being adapted to be carried by a shaft; said members having means forming an overrunning coupling between them; the other of said members having means forming a pair of circumferential channels axially spaced from each other; and a pair of flexible elements having one end respectively secured to said channels of said other member at diametrically opposite sides of said other member, said elements adapted to be wound in said channels respectively in the same angular direction for applying a couple to 6. A device for starting an engine having provisions for overrunning attachment to said engine, said device having a plurality of circumferentially extending flanges forming a pair of longitudinally spaced coaxial annular recesses, the bottom surfaces of the respective recesses being described by substantially equal radii; said device also having provisions for attaching flexible elements for the channels respectively.

7. A device for starting an engine comprising a tubular body adapted to receive the hub of an engine shaft; said body having an inwardly turned flange annularly engageable with said hub for aligning said device with said engine shaft; said body having a plurality of helically arranged recesses at one end to effect an overrunning connection with corresponding projections of said engine shaft; said body having a plurality of circumferentially extending flanges forming a pair of longitudinally spaced coaxial annular recesses, the bottom surfaces of the respective recesses being described by substantially equal radii; and means for anchoring flexible elements in the channels respectively.

8. In a device of the character described: a pair of rotary members, one of said members being adapted to receive the other of said members; said one member having means forming an annular surface engageable with an annular surface of the other of said members for aligning said members; said members having means forming an overrunning coupling between them; the said one member having means forming a pair of circumferential channels axially spaced from each other; and flexible means secured to said one member and having free ends adapted to be wound in the channels respectively for applying a couple to said one member, whereby the forces exerted upon said members by said flexible means are in balance.

9. In a device of the character described: a pair of rotary members, one of said members being adapted to receive the other of said members; said one member having means forming an annular surface engageable with an annular surface of the other of said members for aligning said members; a plurality of equi-angularly spaced pins carried by said other of said members; said one member having at one end thereof a corresponding plurality of helically arranged recesses for receiving said pins respectively to form an overrunning coupling between the members; the said one member having means forming a pair of circumferential channels axially spaced from each other; and flexible means secured to said one member and having free ends adapted to be wound in the channels respectively for applying a couple to said one member, whereby the forces exerted upon said members by said flexible means are in balance.

References Cited in the file of this patent UNITED STATES PATENTS 1,127,804 Pattison Feb. 9, 1915 1,644,932 Mack Oct. 11, 1927 2,063,251 Hertz et a1. Dec. 8, 1936 2,547,010 Jackson Apr. 3, 1946 

